25. Sorry to pee on your pudding but what you say is complete nonsense

organized by Attac, the Left Party, the teachers' union GEW and other groups.

ALL of these events were BANNED by the city government (CDU/Greens). The courts upheld the ban with one exception, the final protest march mentioned in the OP. Wednesday through Friday, subway and train stations adjacent to the banks were shut down and a large police presence all over the city prevented any spontaneous gatherings. 1400 people were arrested:

This beautiful and strong demonstration was the end of a very difficult series of action days. Thousands from all of Europe flocked to Frankfurt to take the squares and block the ECB and other major financial institutions. We were met with total repression. With the exception of the final demonstration, all of our countless planned rallies, demonstrations, assemblies, cultural and educational programs and festivities were banned by the city. We were denied the constitutional right to assemble. We were denied our democratic right to expression. We were denied space to sojourn in the city – with the exception of autonomous student buildings, even the universities were shut down. Democracy was effectively prohibited. At the very least, we can ironically point to one consequence: if we were denied our protest, the police effectively blockaded the city for four days. The European capital of finance was shut down.

We called out to action days in Frankfurt against the austerity policies of the troika and governments. We called out to action and protest against the authoritarian politics implementing these policies. We were met with total repression by the German police. Over 1400* of us were taken into custody for attempting to assemble in the city.

If you understand German, watch the video in the OP where the mingling of the police with the marchers is denounced as provocation. The organizers invite the police to just get lost, buy some ice cream and have a nice day because, sorry, you'll get no violence from us today.

The unprecedented wide-ranging ban of peaceful activities throughout last week was based on the pretext that "some" violent groups "might" participate and, like a few weeks before during the M31 protests might spray some graffiti or smash a window or two. There was never a danger of actual violence taking place, at least not on the part of the protesters. However, if anyone had showed up in the same absurd Ninja gear as the "riot" police, they would have been immediately detained.